Pneumatic hammer.



G. L. ROBERTSON.

PNEUMATIC HAMMER.

APPLICATION FILED JULY 11, 1913. 1,078,384. Patented No v. 11, 1913.

2 SHEETS-SHEET 1.

INVENTOII Georye L. Robertson G. L. ROBERTSON.

PNEUMATIC HAMMER.

APPLICATION FILED JULY 11, 1913.

WITNESSES: INYEIITOR 6807 e L Ralerlsow m STATES PATENT orFIcE.

Gnome newsonnonnn'rson, or PHILADELPHIA, PENNSYLVANIA, Assmxon OF ONE-HALF 'ro cHmEs MITCHELL, or PHILADELPHIA, PENNSYLVANIA.

PNEUMATIC HAMMER.

Specification Letters Patent.

Patented Nov. 11, 1913.

To all whom it may concern:

Be it known that I, GEORGE LAWsoN Ron- ERTSON, a citizen of the United States, residi at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Im provements in Pneumatic Hammers, of which the following is a specification.

My invention relates to improvements in pneumatic hammers, the object of the invention being to provide an improved valve mechanism controlling the reciprocation of the plunger.

A further object is to provide an improved arrangement of ports and passa es and an improved construction of va ve which automatically shifts its position to control the flow of fluid and insure a rapid reciprocation of the lunger.

With these and ot er objects in view, the invention consists in certain novel features of construction and combinations and ar rangements of parts as will be more fully hereinafter described and pointed out in the claims.

In the accompanying drawings: Figure 1 is a view in longitudinal section illustrating my improvements. Fig. 2 is a view in cross section on the line 2--2 of Fig. 1. Fig. 3 is a view in cross section on the line 3-3 of Fig. 1. Fig. 4 is a perspective view of the valve. Fig. 5 is a fragmentary view in section on the line 55 of Fig. 2, and Fig. 6 is a fragmentary view in longitudinal section showing the valve in its forward or shifted position.

1 represents the barrel of a pneumatic hammer having a longitudinal bore 2 in which a plunger 3 snugl fits and is adapted to reciprocate. .The barrel 1 at its rear end is enlarged in diameter and made hollow forming a cylindrical extension 4 in which a valve box 5 is mounted. The valve box 5 is held against rotary movement in the barrel by meansof pins 6, and at its rear end has an annular flange 7 fitting against the end of the barrel. y

The hammer handle 8 is provided with a cylindrical cap 9, internally screw-threaded and engagin screw-threads on the cylindrical extension 4 of the barrel.

Aninternal annular shoulder 10 is provided in the ca which bears against the flange 7 securely inding this flange between said shoulder and the end of the cylindrical extension 4, so that longitudinal movement of the valve box is effectually prevented.

The cylindrical extension 4 has an annular series of ratchetteeth 11 in which a spring-pressed pin 12 engages to'hold the parts against accidental movement.

In the box 5, my improved valve 13 is mounted to reciprocate and has a longitudlnal bore alining with the bore 2 of the barrel, and of the same diameter so that the plunger fits snugly within the valve and reciprocates theret rough.

The valve 13 is open at both ends, its movement in a forward direction being limited by a shoulder 14 in box 5, and the movement in the rearward direction limited by an internal annular flange 58.

The cylindrical central opening or bore of box 5 at its rear end is closed by a cylindrical block 16 forming an integral part of my improved movable box head 17 which is cylindrical in form, and has a leather disk cup 18 secured to a central lug 19 thereon by means of a washer 20. and a pin 21, and this cup 18 with the head 17 is adapted to reciprocate in a cylindrical. casing 22. This casing 22 fits snugly within the fluid inlet chamber 23 at the rear end of the hammer provided within the cap 9, so. that the head 17 is always open to communication with the live fluid pressure entering through inlet passage 24, and is normally pressed forwardly as indicated.

The forward end of the block 16 forming an integral part of head 17 is reduced in diameter and snugly fits within the flange 58, and the rear end of valve 13, so as to form a. cushioning head for an air pocket at the rear end of the valve. This block 16 has a central chamber 25 which communicates by radial ports 26 with an annular groove 27 around the block. This groove 27 is normally out of alinement with radial ports 28 between the end of casing 22 and valve box 5. These radial ports which may constitute a continuous chamber, communicate with longitudinal grooves 29 in the outer surface of casing 22, and I would have it understood that. when I use this term radial ports for the passage 28, that the term is used in its broadest sense.

Casing 22 is secured by screws '30 to the box 5, so that it is held against movement.

'be moved rearwardly until the ports 26 register with the ports 28. Instantly, the live fluid will flow through the ports 26 and chamber 25, and give the plunger its initial forward movement. The action therefore of the head operates to cushion the plunger and admit fluid back of the plunger to accelerate its forward movement. The head will be instantly returned to its normal position by the pressure of live fluid behind the same, but the momentary rearward movement further compresses the fluid and to that extent, increases the power thereof to drive the plunger forwardly.

My improved hammer is provided at its forward end with a removable rivet set 33 and a guard 34, and it is to be understood that the plunger and its reciprocation strikes the set as is customary.

My improved arrangement of passages and ports in the box and barrel are as follows: The longitudinal inlet ports 31 have two outlets 35 and 36, the former discharging directly into an annular groove 37 around valve 13 when the valve is in its rearward position. The ports 32 above referred to communicate with this groove-37, so that the live fluid flows directly into the valve and drives the plunger forwardly. The fluid in front of the plunger exhausts through passages 38 into a circumferential groove 39, thence through radial ports 40 into longitudinal passages 15 which are exhaust passages and discharge at their forward ends into the atmosphere.

When the piston moves forwardly and its rear end uncovers ports 41 communicating with longitudinal passages 42, the live fluid will flow through the longitudinal passages 42 to reverse the valve 13 as will be hereinafter explained.

The valve 13 is provided with an annular enlargement 43 having an annular flange 44 at one end, and an annular groove 45 between its ends. This valve 13 at its rear cylindrical portion is providedwith the an-- nular grooves 37 and 39 above referred to.

The annular flange 44 at one end of the annular enlargement 43 provides a relatively large pressure surface 46 on the rear end of the enlargement and also provides a relatively small pressure surface 47 on the forward side of the flange. The forward end of the cylindrical enlar ement 43 forms an annular shoulder 48 w ich moves toward and away from an internal shoulder 49 in the valve box forming anv annular air space 50 which is connected at all times by radial ports 51 with the passages 15, so that this air space 48 is in constant communication with the atmosphere and prevents partial vacuum or compression, allowing the valve to freely reciprocate without opposition from these surfaces.

The relatively large pressure surface 46 moves toward and away from an annular shoulder 52 in the valve box, and the space between said pressure surface 46 and the shoulder 52 communicates with the longitudinal passages 42 above referred to.

The relatively small pressure surface 47 is always in communication with the live fluid through the medium of longitudinal passages 53 in the valve box which connect the passages 31 with the space in front of the pressure surface 47.

The annular groove 45 in valve 13 is adapted when the valve is moved forwardly to connect longitudinal passages 54 with radial passages 55, the latter communicating with the exhaustpassages 15. The passages 54 are relatively short, and operate as exhaust passages when the plunger is on'its rearward stroke. v

The operation is as follows: In Fig. 1 the plunger is movin forwardly and the live fluid is entering through passages 31, ports 35, and openin s 32, driving the plunger forwardly. The flilid in advance of the plunger is forced through the passages 38, groove 39, ports 40, and passages 15 to the atmosphere. When the lunger uncovers ports 41, the live fluid will ow through passages 42 and exert pressure upon the pressure surface 46 to drive the valve to its forward position. Immediately the live fluid will pass through passages 31 and ports 36, thence through groove 39 and longitudinal passages 57 to the forward end of the barrel to drive the plunger rearwardly. The fluid in front of the plunger will be forced through passages 54, groove 45, radial ports 55, and exhaust ports 15. A portion of this air in front of the plunger will also be forced out through openings 32, groove 37, and radial ports 56 into passages 15. When the forward end of the plunger on the rearward stroke of the latter uncovers passages 54, a portion of the live fluid will escape to the atmosphere, relievingthe pressure on surface 46, allowing the pressure of live fluid on surface 47 to shift the valve to its rearward position. As the plunger completes its rearward stroke, it will be cushioned by the action of the head 7 as above explained, and will immediately begin its forward stroke.

Various slight changes might be made in the general form and arrangement of parts described without departing from. my inven-.

tion, and hence I do not limit myself to the precise details set forth, but consider myself amass.

Having thus-described my in-vention, what I claim'as new and desire'to' secure by-Letters Patentis':

1. In a pneumatic hammer, the'combina" tionwith a barrel, and a reciprocating plum ger in the barrel, of aval-ve box secured to the=barrel, areciprocating- *valve in the boxthrough which the plunger'moves, said valve *and'box constructed .to form an annularair faces of different areas, fluid passages in the space adjacent the forward end of the "valve,

.andsaid air space always maintained in'communicat-ion' with the-outside air, said valve having two-annular opposed pressure sur faces of different areas, and fluid assages in theba'rrel and box controlled by t e plunger= for re ulating-the pressure against one of the su aces to'compel-the valve'to reverse a I as the-plunger nears the ends of its stroke, substantially asdescribed.

2. In a pneumatic hammer, the combination with a barrel, and areciprooating plun ger in the=barrel, of' a-valve box secured to thebiarrel, a reciprocating valve in the box' through whichthe lunger moves, said valve and boxconstructe to form an annular an" space adjacent the forward end of'zthe valve, and-said airspace always maintained in communication with the outside air, said valve having two annular opposed pressure surfaces of different areas, and fluid passages in the barrel and box'controlled by the plunger for-regulatingthe pressure against one of the surface to-'compel the valve to reverse as the plunger nears-the ends-of its stroke, and said valve having ports therein registering-with the-passagles-in: the box, and con trolling the flow of uid to operate't-he plunger, substantially as describedu 3; In a pneumatic hammer, the combina- .tion' with a barrel; and a reciprocating plunger in the barrel, of 'a valve box -secured to the barrclg' aurec-iprooatingwalve in'the box through which the plunger moves, said-valve and box constructed to form' an annular air space adjacent the forward end of the valve, and said air space always maintained in communicatiomwiththe outside air, said valve having two annular opposed pressure surharrel and bOX'COlltlOllQd by the plunger for -regulating the pressure against one of the sur-' faces to compel the valve to reverse as the plunger nears the ends of its stroke, the

smaller of said surfaces always in commun1- cation with the live fluid, and the larger of said surfaces in communication with the live fluid during a porti on only of the stroke of the plu er, substantially as described.

4. In a pneumatic hammer, the combination with a barrel, and a reciprocating plunger in the barrel, of a valve box secured to the barrel, a reciprocating valvein the box th rough which the plunger moves; said valvm. and box-constructed :to-form 1 an annular air space adjacent thejferward end of the valve,

and said air space always-maintaincdincomeinunication' with the outside air, saidvalve having I two annular opposed pressure sure 'faces-ofd iflerent-areas, fluid passages in=thebarreland-boxcontroIled by the plunger forregulating-mhe-pressure against onset the surfaces tocompel the-valve to reverse as the plunger nears-the ends =of-its stroke, and

said valve =having ports= therein registeringwith the passages in the-box; and controlling the fiow o-ffluidto operate thse plunger,"thc-- smaller of said surfaces always in communication with thelive fluid, and the larger of said surfaces in communication with thelive fluidzdu ring aortion only. ofthe stroke of the plunger, suiistantiallv as described.

5.. In a. pneumatic hammer; the combina tion with arbarrcl, and areciprocatingfplun ger-in the barrel, of a valvebox secured to the barrel, anreciprocating valvein the box through which the plunger moves, said valve and box constructed. to form annular air space adjacent the forward end of-thcmalve, and said air space always maintained in com,-

munication with: the outside-air, said valve having two annular opposed; prexure sur faces oftdtifierent areaS fluid passages in the; barrel and box controlledhy the plunger forregulating: the pressure against-oneofthe;

surfaces-to compel the-valve to reverse as the plunger-nears the=ends of its stroke, saidopposed surfa'cesformed by an annular flange at one end of an annular enlargement; on-thezvalve; theother end'of said annular enlargement :always in communication with. thezatmosphere, substantially as described: 6: In arpneumatichammer, the combination with a barrel, and a. reciprocating plunger in: the barrelflof a valve-box secured: to V the barrel,- aaeciprocating valve in the boxthrough" which the plunger moves, said:

valvesand boxconstructedto forman annularai-rspace adjacent the forward end of the; valve, and said air spacealways main: tained in xcommunication: with the outside air, said valve having two annular opposed pressure surfaces of different. areas, fluid.

passe es in the barrel and box controlled bythe plunger for regulating the pressure against one of the surfaces to compel the valve to reverse as the plunge" nears the ends of its stroke, said valve having ports therein registering with the passages in the box, and controlling the flow of fluid to operate the plunger, said opposed surfaces formed by an annular flange at one end of an annular enlargement on the valve, the 126 other end of said annular enlar ement always in communication with t e atmosphere, substantially as described.

7. In a pneumatic hammer, the combination with a barreh'and a reciprocating plun- 1'80 7 tion with a barrel, and a reciprocating plunger in the barrel, of a yalve'box secured to -the barrel, a reciprocating valve 1n the box through which the plunger moves, said valve and box constructed to form an annu- 5 lar air space adjacent the forward end of the valve, and said air space always maintained in communication with the outside air, said valve having two annular opposed pres sure surfaces of different areas, fluid passages in the barrel and box controlled by the plunger for regulating the pressure against one of the surfaces to compel the valve to reverse as the plunger nears the ends of its stroke, the smaller of said surfaces always in communication with the live fluid, the larger of said surfaces in communication with the live fluid during a portion only of the stroke of the plunger, said opposed surfaces formed by an annular flange at one end of an annular enlargement on the valve, the other end of said annular enlargement always in communication with the atmosphere, substantially as described.

/ 8. In a pneumatic hammer, the combinager in the barrel, of a valve box secured to the barrel, a reciprocating valve in the box through which the plunger moves, said valve 30 and box constructed to form an annular air space adjacent the forward end of the "alve, and said air space always maintained in communication with the outside air, said valve having two annular o posed pressure surfaces of different areas, uid passages in the barrel and box controlled by the plunger for regulating the pressure against one of the surfaces to compel the valve to reverse as the plunger =nears the-ends of its isterin with the passages in the box, and contro ing the flow of fluid to operate the plunger, the smaller of said surfaces always in communication with the live fluid, and the larger of said surfaces in communication with the live fluid during a portion only of the stroke of the plunger, said opposed surfaces formed by an annular flange at one stroke, said valve having ports therein regend of an annular enlargement on the valve, the other end of said annular enlargement always in communication with the atmosphere, substantially as described.

9. In a pneumatic hammer, the combination with a barrel, and a reciprocating plunger in the barrel, of a valve box secured in the barrel, a reciprocating valve in said box through which the plunger moves, said valve and box constructed to form an annular air space adjacent the forward end of the valve, and said air space always maintained in communication with the outside air,

said valve having two annular opposed pressure surfaces of different areas agamst which fluid is always directed tending to move the valve in both directions, and said barrel and box having fluid passages therein controlled by the plunger, whereby the pres sure against one of said opposed pressure surfaces is regulated to compel the valve to move from one operative position to another, substantially as described.

10. In a pneumatic hammer, the combination with a barrel, and a reciprocating plunger in the barrel, of a valve box secured in the barrel, a reciprocating valve in said box, said valve having a cylindrical bore through which the plunger moves, and havin two pressure surfaces adjacent its rear en one smaller than the other, said valve having an annular surface opposing anannular surface in the'box, said last-mentioned surfaces forming an air space maintained always 1n 

